The Types of Storage Tank Settlement & How to Mitigate Them

Katelyn Gustoff, consulting engineer, and Derek Slovenec, senior engineer, from The Equity Engineering Group explore this threat to asset integrity Foundation settlement poses a significant threat to the integrity of aboveground storage tanks (ASTs). Correcting excessive settlement typically requires major repairs including re-levelling the foundation and replacing components that have experienced excessive plastic strain. Re-levelling of a sizable tank is expensive and has certain risks associated with the procedure; thus, deciding to re-level an AST is crucial and relies on the proper interpretation and evaluation of the monitored settlement data. ASTs are inherently flexible structures so significant foundation settlement can often be tolerated. Settlement evaluation methods are provided in API 653 Tank Inspection, Repair, Alteration, and Reconstruction¹ (API 653) to evaluate an AST’s suitability for service. Alternatively, API 579-1/ASME FFS-1 Fitness-For-Service (API 579) can be referenced to supplement the API 653 guidance and provides a more rigorous means to evaluate the fitness for service (FFS) of an AST undergoing settlement. This article will take a detailed look...